Published: May 28, 2012

CHULA VISTA, Calif. — Connor Fields lounged on his BMX bike this month at the Olympic Training Center. While most of his fellow riders met with representatives from Oakley, Fields surveyed the track, a replica of the one riders will race on at the London Olympics, and noted his disdain for goggles.

Jonathan Fennell for The New York Times

Jonathan Fennell for The New York Times

“My first impression?” Coach Herrera said of Fields, above. “A cocky, young punk with skills to match. And he still races that way.”

Asked why he elected not to wear them, what with the dirt and the rocks and the competitors on small bikes that can reach 40 miles per hour, Fields laughed. “You don’t get hit if you’re in front,” he said.

His coaches watch Fields on his bike and see no obvious historical comparison. Only 19 years old, Fields has won three consecutive World Cup final races, a first in the young BMX racing discipline of supercross, in which a handful of seconds separate the top slot from the bottom.

But Fields’s rise to favorite for the London Games is not the tidy narrative of an athlete with transformative talent. His is the story of a father who acknowledged that he pushed his son too hard, of a coach who lost his job but not his pupil, of a rider who enrolled in college and almost quit BMX.

“We have these moments where we watch him, and we’re like, ‘He’s really going to hurt himself,’ ” said Mike King, the BMX program director for USA Cycling. “And then, at the last millisecond, he can bring his bike back together. He’ll throw it sideways, and when it looks like he’s going into the face of the jump, at the last second, he’ll land it, and you can see the body weight, the transition, the burst of speed he creates.

“I watch in amazement. You can’t teach that.”

To label Fields confident, King said, “would be putting it pretty mildly.”

Fields does not disagree with that assessment. In fact, he said he compiled this stellar BMX season because he learned the difference between cocky and assured. (“My first impression?” the national team coach, James Herrera, said. “A cocky, young punk with skills to match. And he still races that way.”)

The most important lesson took place in 2010, at the junior world championships in South Africa. Fields led every lap he raced until the final one. He led that, too, at the beginning, but he continued to push harder, harder, harder, because he wanted to obtain the fastest lap time of the weekend. His mentality: “kill everybody” and “destroy the competition.”

But Fields crashed, while ahead by three bike lengths, a more than comfortable margin. He cried in the arms of his coach, Sean Dwight, for 20 minutes. The crash also aggravated a knee injury, which led to Fields’s first extended absence from BMX.

His father, Mike, said Fields sank into depression when he missed seven months in late 2010 and early 2011 because of the injury and its aftermath. He rarely came out of his room. For days, he watched “Lost” and played war video games online. He even went so far as to register for classes at the University of Nevada, Las Vegas, the goal to ultimately become a physical therapist.

“We thought we had lost our son,” Mike Fields said.

Eventually, Connor Fields summoned the courage to call Dwight, a no-nonsense Australian who listened to Fields’s plan to quit and told him: “I’m going to say this once. You have the ability to win the Olympic Games.”

Fields had spent most of his life preparing for such BMX supremacy. At 7, his parents purchased a bike to channel their son’s unlimited energy. Halfway to his first race, Fields already had his helmet on.

His father watched the way Fields reacted after losses, how he retreated into corners and cried for hours, how over time the tantrums lessened but how “he never really got out of this horrible unhappiness if he didn’t win.”

No one could quite explain the drive, but for Mike Fields it felt familiar. He felt it, too. As he retold the story, he paused, choking back emotion. “My biggest fear was I was losing him as a dad,” he said. “I realized I wanted it more than he did. That I wanted it too much.”

His most important lesson came at a Father’s Day race, where fathers of competitors rode the course before their sons raced. Mike Fields crashed on three of the four laps and ripped his jeans and shirt: a humbling experience for the former rugby player.

Now Mike Fields likes to say he has gone from a BMX roadie to a superfan. He still travels the world to watch his son race, but he leaves the coaching to Dwight, King and others. Mike Fields is allowed to come to dinner, but he cannot talk about BMX.

While most BMX races are won in the first few seconds out of the gate, Fields, long a notoriously slow starter, prevailed with the way he attacked the rest of the course. In recent years, his starts have also improved, to the point where if Fields speeds down the first ramp even with the other riders, King said, he should win almost every time. His latest triumph was at the world championships on May 25 in Birmingham, England, where he won the elite men’s time trial superfinal.

Dwight, who once worked for USA Cycling, serves as Fields’s primary coach. He helped Fields overcome his injury, even hosted Fields in Australia for training. The family pays many of his expenses, including flights and lodging for competitions. The dynamic with USA Cycling can be awkward, but so far, especially lately, it has worked.

“Every so often a sport evolves,” Dwight said. “Connor is a new breed. He’s redefining the way the sport should be approached, and he’s rewriting the history of BMX, right now.”

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A version of this article appeared in print on May 29, 2012, on page B9 of the New York edition with the headline: The Best and the Brashest.